The present invention relates to a carbonaceous or carbon film such as formed on a substrate and a treating method thereof, and more particularly to a carbon film which can be applied, for protective, insulative, surface modification or other purpose, to a variety of mechanical, chemical and electronic components that require the characteristics of high wear resistance and corrosion resistance, including electric shaver blades, compressor components, masks (screens) and squeegees for use in printing and surface acoustic wave devices, and to a method of treating thereof. The present invention also relates to a component with such a carbon film.
Carbon films, because of their excellent mechanical and chemical stabilities, have gained great expectations as coating materials. However, such carbon films exhibit higher affinity for water (less hydrophobic) at surfaces. This problematically permits easy adhesion but hard removal of dirt. Another problem has been encountered in components coated with a carbon film, i.e., they tend to be electrostatically charged as a result of easy generation of static charges at their sliding surfaces.
These have necessitated a treatment whereby the forming conditions of carbon films are varied or various materials are incorporated into films.
However, the practice of such treatments impairs their intrinsic mechanical and chemical properties, resulting in limiting the applicable field of carbon films.
The present inventors have found that the modification of a carbon film only at its surface permits improvements in hydrophobicity and electrical conductivity of the film surface without impairing intrinsic properties of the carbon film.
It is an object of the present invention to provide a method for treating a carbon film, which can modify surface properties of the film without impairing the characteristics of the carbon film.
The method for treating a carbon film in accordance with the present invention is characterized as comprising, in sequence, depositing a carbon film on a substrate by a plasma CVD technique and exposing a surface of the carbon film to a plasma so that the carbon film is modified at its surface.
In the present invention, the deposited carbon film is preferably exposed to the plasma produced utilizing at least one gas selected from an Ar gas, N2 gas, H2 gas and F-containing gas. The F-containing gas may be at least one selected from a CF4 gas, SF6 gas, NF3 gas and F2 gas.
Preferably, the deposited carbon film is exposed to a plasma produced using a B-containing gas and/or a P-containing gas, as well as to the above-described plasma.
During plasma exposure, a bias voltage may preferably be applied to one of the carbon film, the substrate having the carbon film deposited thereon and a substrate holder by which the substrate is held in position. Preferably, the bias voltage applied is a substantially negative voltage. More preferably, it is a negative voltage of at least xe2x88x92300 V, i.e. from below 0 V to xe2x88x92300 V.
In the present invention, deposition of a carbon film and the subsequent plasma exposure are preferably effected in the same apparatus.
Also in the present invention, a region of the carbon film that is modified by exposure to the plasma preferably extends to a depth of at most two thirds of its thickness.
The carbon film, as used herein, can be illustrated by amorphous carbon films, such as diamond-like carbon films, but may include a localized crystalline region.
The carbon film of the present invention is the carbon film characterized as having been treated by the treating method of the present invention.
The component of the present invention is the component having at its surface the carbon film treated by the treating method of the present invention. Examples of such components include a mask for use in screen printing, an inner or outer blade of an electric shaver, a stationary or rotary cylinder of a VTR and the like.